DAYTONA BEACH, Fla.—Kevin Harvick has found a winning routine at Speedweeks.

It involves putting his infant son, Keelan, behind the wheel before races.

It worked before the Sprint Unlimited last Saturday night and again Thursday in the first of two qualifying races for the Daytona 500. Harvick claimed the first Budweiser Duel race, edging Greg Biffle and making him 2 for 2 during the first two weeks of racing in 2013.

Sure, Harvick has one of the fastest cars at Speedweeks. But there's little doubt being a father—wife DeLana gave birth last July—has had a calming effect on a driver who has been temperamental at times during his 12-year career.

"It's added a new balance to my life where I can still come to the racetrack and I feel like I'm more relaxed and more focused, which is good for me," Harvick said. "I don't get as wound up on things when they happen, whether it's in the car, outside the car.

"When you've had a bad day, you're frustrated, you're right to the point where you can say something stupid, you go back to the motor home, you see that smiling face, it lets you get your mind off of things. It's added a great balance to my life. I think it's made me better."

Television cameras caught Harvick waiting outside his motor home after Thursday's race while Keelan took a nap. Harvick arrived at his motor home to find a "baby is sleeping" pillow hanging on the door, a warning that prompted him to relax in a lawn chair outside.

"At the racetrack, his focus is still there," Martin said. "As he leaves the racetrack, with having his son to go back to, you don't have to go in and look for some excitement outside of the track; it's already there waiting on him.

"I think with that being in his life now, it's going to do nothing but help him and direct his focus on Sunday. I'm looking forward to watching what happens."